Polyolefin composition

Abstract

A polyolefin composition is described, comprising: (A) a polyolefin which is modified with an unsaturated carboxylic acid or its derivative, or a mixture of such a modified polyolefin and a polyolefin, (B) aluminum or aluminum alloy in a powdery, fibrous and/or flaky form, (C) electrically conductive carbon black, (D) a halogen-containing organic compound and antimony oxide, and (E) a hydrous inorganic substance. This polyolefin composition has good electromagnetic wave-shielding properties and flame resistance, and therefore, it can be used as a housing material for electronic equipment.

What is claimed is: 
     
       1. A polyolefin composition comprising: (A) 90 to 40% by volume of a polyolefin which is modified with an unsaturated carboxylic acid and/or its derivative, wherein the unsaturated carboxylic acid and/or its derivative content of Component (A) is from 0.01 to 1.0% by weight;   (B) 5 to 50% by volume of aluminum or an aluminum alloy;   (C) 5 to 50% by volume of electrically conductive carbon black, the proportions of Components (A), (B), and (C) being based on the total volume of Components (A), (B) and (C);   (D) 5 to 30 parts by weight, per 100 parts by weight of Components (A), (B) and (C), of a halogen-containing organic compound and antimony oxide; and   (E) at least 5 parts by weight, per 100 parts by weight of the carbon black, of a hydrous inorganic substance.   
     
     
       2. A polyolefin composition comprising: (A) 90 to 40% by volume of a mixture of a polyolefin and a polyolefin modified with an unsaturated carboxylic acid and/or its derivative, wherein the unsaturated carboxylic acid and/or its derivative content of Component (A) is from 0.01 to 1.0% by weight;   (B) 5 to 50% by volume of an aluminum or aluminum alloy;   (C) 5 to 50% by volume of electrically conductive carbon, the proportions of Components (A), (B) and (C) being based on the total volume of Components (A), (B) and (C);   (D) 5 to 30 parts by weight per 100 parts by weight of Components (A), (B) and (C), of a halogen-containing organic compound and antimony oxide; and   (E) at least 5 parts by weight, per 100 parts by weight of the carbon black, of a hydrous inorganic substance.   
     
     
       3. A polyolefin composition as claimed in claim 1 or 2, wherein the aluminum or aluminum alloy is in a powdery form, a fibrous form, or a flaky form. 
     
     
       4. A polyolefin composition as claimed in claim 1, wherein the unsaturated carboxylic acid or its derivative is selected from the group consisting of maleic acid and maleic anhydride. 
     
     
       5. A polyolefin composition as claimed in claim 1 or 2, wherein the polyolefin has a molecular weight of from 20,000 to 1,000,000. 
     
     
       6. A polyolefin composition as claimed in claim 5, wherein the polyolefin has a molecular weight of from 20,000 to 500,000. 
     
     
       7. A polyolefin composition as claimed in claim 6, wherein the polyolefin has a molecular weight of from 50,000 to 300,000. 
     
     
       8. A polyolefin composition as claimed in claim 1 or 2, wherein the total proportion of Components (B) and (C) ranges from 10 to 60% by volume based on the total volume of Components (A), (B) and (C). 
     
     
       9. A polyolefin composition as claimed in claim 8, wherein the total proportion of Components (B) and (C) ranges from 25 to 50% by volume. 
     
     
       10. A polyolefin composition as claimed in claim 1 or 2, wherein the volume ratio of Components (B) to (C) ranges from 2.5/1 to 1/2.5. 
     
     
       11. A polyolefin composition as claimed in claim 1 or 2, wherein the proportion of Component (E) ranges from 7 to 20 parts by weight.